Download Karyotypes: Mutations and Diseases

Karyotypes: Mutations and
Diseases
Gene Mutation vs. Chromosomal
Mutation
Gene Mutation
• Affects only one gene
(protein) on a
chromosome:
• Example:
– sickle cell anemia
(hemoglobin protein)
– Cystic fibrosis
Chromosomal Mutation
• Affects a group of
genes or entire
chromosome:
• Example:
– Down syndrome
– Klinefelter’s syndrome
– Turner’s syndrome
Sickle Cell
(auto. recessive)
• GENE MUTATION: only
affects one gene on
chromosome 11
(hemoglobin).
• Autosomal recessive gene.
• Symptoms:
–
–
–
–
Pain/infections
Delayed growth
Strokes
jaundice
Cystic Fibrosis (auto. Recessive)
• GENE MUTATION:
only affects one gene
on chromosome #7.
• Affects respiratory
and digestive systems.
• Autosomal recessive
gene.
• Symptoms:
–
–
–
–
Coughing/wheezing
Weight loss
Salty-tasting skin
Most don’t live much over
30.
Nondisjunction
• Examples of nondisjunction
• Offspring with an
on:
incorrect number of
chromosomes.
• Sex chromosomes:
– Klinefelter’s syndrome (XXY)
– Turner syndrome (only one X).
• Normal chromosome
• Autosomes:
number: 46
– Down syndrome (3 copies of
• Nondisjunction:
chromosome 21).
normally 45 or 47.
• Pairs of
chromosomes are
not pulled apart
during gamete
formation.
Trisomy
• Presence of an extra
chromosome.
• Three chromosomes
instead of a pair.
• Types:
– 21 (Down syndrome)
– 18 (Edwards
syndrome)
– 13 (Patau syndrome)
Down Syndrome
• Caused by
nondisjunction.
• Extra copy of
chromosome #21.
• Symptoms:
–
–
–
–
–
Distinct facial features
Respiratory infections
Leukemia
Heart defects
Many more…
Klinefelter’s Syndrome
• Caused by
nondisjunction.
• Occurs only in
males.
• Males have extra
X chromosome
(XXY).
• Symptoms:
– More breast tissue
– Less muscular body
– Grow little facial or
body hair
– Cannot produce
sperm.
Turner Syndrome
• Caused by
nondisjunction.
• Develop as females.
• Missing X
chromosome.
• Symptoms:
– Stocky appearance
– Arms turn out at
elbow
– Short webbed neck
– Swelling of hands and
feet